Problem: Kevin is 5 times as old as Ben and is also 36 years older than Ben. How old is Kevin?
Explanation: We can use the given information to write down two equations that describe the ages of Kevin and Ben. Let Kevin's current age be $k$ and Ben's current age be $b$ $k = 5b$ $k = b + 36$ Now we have two independent equations, and we can solve for our two unknowns. One way to solve for $k$ is to solve the second equation for $b$ and substitute that value into the first equation. Solving our second equation for $b$ , we get: $b = k - 36$ . Substituting this into our first equation, we get the equation: $k = 5$ $(k - 36)$ which combines the information about $k$ from both of our original equations. Simplifying the right side of this equation, we get: $k = 5k - 180$ Solving for $k$ , we get: $4 k = 180$ $k = 45$.